Climate Control: Air recirculation Failure

[Richard1]

My 87 560 SL's air recirulation is working intermitently...I push the circulation button, it works for a bit, and then stops working...what could the problem be? Thank you.

[pmizell]

Richard:

The air recirculation system is designed that way. It will remain on for 30 minutes, then shuts off automatically. However, after shutting down, you still receive 80% recirculated air and 20% outside air if I remember correctly. This is I believe to prevent mold/mildew from forming inside your AC system.

According to the CD manual, it is possible to switch the system to 100% recirculated air for an unlimited period (quoting) if with outside temperatures above 20c, the temperature selector wheel is engaged in the "Min" position.

The MB AC systems are very advanced ... and do alot more than you think they might -- even the older models like your '87. The CD manual has a 35 page PDF document explaining the intricacies of the system, just to give you an idea.

~Paul

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'91 300E, 207k miles

[400E]

Richard,
In addition to what Paul has said, the amount of time the recirc mode stays on after you push the button depends on outside air temperature. In cold weather, it may only recirculate for 5 minutes; in warm weather it's longer.

It's designed (thoughtfully, I think) to prevent us from fogging up our windows in the winter by leaving it in the recirculation mode.

You can get more details in your owner's manual.